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jeffrey 07-06-2009 05:10 PM

how to bend a revolver mainspring?
I would like to know how to bend a stock S&W revolver mainspring to get a lighter trigger pull. I know that I can just buy reduced power Wolf springs and have bought them in the past. But having put Wolf springs in a bunch of guns, I now have a bunch of stock mainsprings and Id like to see what I can do with them.

A gunsmith once did this for me and the result was pretty good, not quite as smooth or light as a Wolf, but noticeably better than before. Also, this bent spring gave me a trigger pull that was a bit heavier than a Wolf spring and worked with primers that were too hard for that particular gun using a Wolf reduced power mainspring.

I got a nylon wedge from Brownells (that they advertise for this purpose) but I don't know how to use it.

Thanks for any advice you all can provide!

bountyhunter 07-06-2009 06:38 PM

You need to do what's called a "mandrel" bend which just means bend it over a curved form so you don't put a corner in it. I get three screwdrivers with round plastic handles (maybe 1 1/4" diameter) and set them up so the bend is centered about 2/3 of the way up from the bottom tip of the spring. Two screwdrivers on one side, one on the other so you are bending across the single one.

Before you start, lay the spring sideways and ink a line showing the starting curve so you can compare it after you bend it. To reduce strength, bend a little more curve into it. To make it stronger, you flatten it some.

jeffrey 07-08-2009 12:49 AM

Thanks bountyhunter. I will try it.

imashooter2 07-08-2009 08:11 AM

I like to bend mine similar to the Wilson or Miculek reduced springs and use a simple jig made of 2 nails set into a 2x4. Use one small nail that will engage the hooks and add another larger nail about an inch away to use as the bending point. Easy to control and repeatable.

jeffrey 07-08-2009 04:10 PM

Thanks Imashooter. Does anyone use the nylon wedge from Brownells? I'm curious because now that I've got it, I might as well use it.

bountyhunter 07-08-2009 05:49 PM


Originally Posted by jeffrey (Post 1006516)
Thanks Imashooter. Does anyone use the nylon wedge from Brownells? I'm curious because now that I've got it, I might as well use it.

Maybe you could post the part number, I never heard of it.

jeffrey 07-08-2009 09:28 PM

"Nylon wedge" is the name and 080-722-100 is the part number. Thanks for taking the time to give this some thought.

imashooter2 07-08-2009 11:12 PM

I can't see how that could be used except to wedge in between the frame and the spring to try and bend it while still installed in the gun...

I can't picture someone actually doing that, but I can't see any other way to use it.

bountyhunter 07-09-2009 01:28 AM

I don't think I would use that.

sal1911a1 07-09-2009 08:16 AM


Don't bend springs, or cut coils from trigger rebound springs all that is bad bad bad:(

If you must, and have to have a lighter spring(God knows why) pick a Wolf spring and install it, I have seen too many shooters turn there revolvers into junk real fast, improper bending will change smooth action into ****. Also add unnecessary stress to adjoining parts, remember the trigger pull is a long cycle all the parts depend on one another for fit and proper spring tension,

The short answer install a Wolf Type II is reduced power, Type one is factory power. They have a bend in the proper area and the right temper.

Pdxrealtor 05-19-2016 04:11 PM

Old thread I know. However, I wanted to say that S&W bends the Wolff mainspring when adjust trigger pull to 10 lbs on their PC guns. Bend in the middle, no kinks, and measure pull weight. Adjust as needed.

I personally like the Wolff Reduced power spring and a socket set screw with the proper loc-tite. I think Tomcatt51 turned me on to that.

flintsghost 05-19-2016 06:22 PM


Originally Posted by jeffrey (Post 1006516)
Thanks Imashooter. Does anyone use the nylon wedge from Brownells? I'm curious because now that I've got it, I might as well use it.

The Nylon wedge you are referring to is used as a take down tool to disconnect the mainspring from the hammer without unscrewing the mainspring strain screw. In the S&W armorers kit it is a wooden wedge. Brownells made it of nylon for it's longer lasting properties over wood.

scattershot 05-19-2016 08:49 PM

I just checked the Brownells site, ans they indicate that it can be used to re-arch the Mainspring. They have a live chat feature on the website, you,could ask,them about it. I've never seen one of those, so I can't offer any advce.

dfariswheel 05-19-2016 08:50 PM

The primary purpose of the wedge is to be used to straighten cylinder yokes that are sprung.

If the cylinder is sprung upward, the wedge is pushed in between the frame and the closed cylinder, then tapped to bend the yoke.

I strongly suspect that if you try to bend the spring in the frame, what will happen is that you'll break the "fingers" on the spring or break the hammer stirrup the spring connects to before you get a bend in the spring.

These days with so many after market springs available, it's not really necessary to bend springs.
Instead you can install a after market spring and tune the spring tension screw to get whatever you want.

crsides 05-20-2016 01:07 AM

Yrs ago, I send my 29-2 to 300 gunsmith services in Colorado for an action job. It came back sweet. They bent the mainspring just below the hooks. At the time, it was a normal procedure that required taking the temper out of the spring, bend it, and re temper the spring. I just buy another Wolfe spring these days.


jack the toad 05-20-2016 10:11 AM

A little off topic as to bending the spring but does lighten the spring. I'm not recommending or advocating doing it but I've seen it done. By lightly grinding on a belt sander, going slow not to overheat but to narrow the spring width. I guess maybe the same thing might be achieved by thinning the spring thickness rather than the width but I've not seen that done. I'm not an expert so regardless, I think bending would be better and with the availability of relatively inexpensive springs, a replacement would probably be better still.

StakeOut 05-20-2016 10:32 AM

If you get all rounds to fire and your double action pull is smooth between 8 and 9 lbs leave it alone.

If you must play with your action then back out the stain screw a 1/4 turn at a time till you no longer get good primer hits with all rounds firing.Then back it in 1 full turn.

I've done the Wolff Spring thing on a few Smith revolver and always go back to the factory springs and full strain on the mainspring.

First and foremost the revolver must be able to fire all rounds consistently.Anything less is a fail.

chief38 05-20-2016 11:10 AM

I would NOT bend a Smith Main Spring - but that's just my opinion. I have removed minor amounts from Strain Screws to lessen the pressure on the Main Spring and if necessary (although I have never needed to do this) a lighter one can be substituted in the originals place.

The only springs that I do bend for adjustments are the three finger springs in 1911's. Other than that, I do not bend them.

Big Cholla 05-20-2016 11:23 AM

I don't care what named gunsmith or manufacturer 'bends' mainsprings while 'doing' a trigger job. It is a bad metallurgy practice and can lead to real problems. If your gun is a paper puncher, do anything you want. If it has any chance of being needed for self defense purposes.....leave the mainspring alone or buy an after market quality spring like produced by Wolff......

clang444 05-20-2016 11:54 AM

This is an interesting old thread, I am happy it was resurrected.

I have a 1st Gen Colt SAA circa 1904 that has been changed to a .38 Special with 2nd Gen parts. It's been fired a lot - so much so that the cylinder ratchet has peened the recoil shield. It's got about the smoothest and lightest cocking I've ever felt on a SAA.

Part of that is from use, but it also has a mainspring that has been worked on. It looks like someone used a flat file to round off the back side of the mainspring so that it is a convex arch from side to side. The spring looks very old and I know I've shot it plenty of times with no issues.

The gun is 100% reliable and I've never had light primer strikes. It makes me wonder if a S&W mainspring can be modified the same way.

iPac 05-20-2016 01:02 PM

Buy the Jerry K. shop manual for S&W revolvers.

I am sure it will tell you proper ways to reduce trigger pull.

In my experience, S&W has always had a decent SA pull, meaning quite light compared to others.

For my 629-2E, the SA pull was excellent, but the DA pull was horrendous and probably 15lbs+ if I could accurately measure it.

I installed an 11lb rebound spring, then modified and adjusted the tension screw on the mainspring until it would successfully rebound the trigger.

The SA is about 2.5lbs and the DA is about 9lbs now. Very smooth.

Hapworth 05-20-2016 03:35 PM

I'm with the buy Wolff springs camp if you want to tinker with springs, but there are many ways up the mountain to also include bending and grinding them, and shaving down the strain screw.

One note of caution in doing anything to the older S&W mainsprings, say, prior to 2000 or so; I've found that current factory mainsprings are thicker compared to the old days, and the result is a heavier and sometimes hitchier action. They're not making the old mainsprings anymore and I'd leave them be.

dfariswheel 05-20-2016 07:51 PM

For many years people filed or ground mainsprings to lighten the tension even though experts said not to do it because the spring would sooner or later snap.
They did it anyway and were often shocked when the spring snapped soon after.

What happens is, the filing or grinding leaves scratches, often microscopic and those cause stress risers in the structure of the spring. That causes the spring to snap.
People were warned that any filing or grinding required extensive smoothing of the spring to remove even scratches that couldn't be seen to eliminate the stress risers, but even then the springs still tend to snap.

Again, with all the different types and brands of S&W mainsprings available, bending or grinding of springs is a relic of a different era before after market springs were available.

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